Stage 1

Nonblanchable erythema of intact skin (skin remains erythematous under pressure). Can be superficial or represent deep tissue damage. Persons with dark skin can be difficult to evaluate for this stage.

Stage 3

Stage 4

Extend into bone or muscle. Ulcers are associated with extensive damage and necrosis. Prosthetic joints or other implanted foreign bodies may be visible in the wound. Undermining or sinus tract formation is often present.